Climate change and human health

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Climate change 2014: impacts, adaptation, and vulnerability

Overview

The latest report on climate change from the Intergovernmental Panel on Climate Change (IPCC), released on March 31, documents the evidence on the scale and nature of the health risks arising from climate change, as well as the potential benefits that could be achieved by measures to cut greenhouse gas emissions.

The IPCC constitutes arguably the largest scientific assessment exercise in human history. The five assessment reports it has released since 1988 have been assembled by several thousand authors, and document the now overwhelming evidence that human activities have been the major driver of recent warming of the earth’s surface, and that both climate change, and its consequences, will continue into the future.

This latest report covers evidence on the impacts of climate change and adaptation measures for different regions, natural and human systems – including health.

Health problems exacerbated

The health assessment, firstly, confirms and expands the evidence base on the health risks presented in the previous assessment report, in 2007.

This includes the much stronger evidence that negative health impacts will outweigh positive effects. It concludes that climate change will act mainly, at least until the middle of this century, by exacerbating health problems that already exist, and the largest risks will apply in populations that are currently most affected by climate-related diseases.

It supports the case that under-nutrition resulting from reductions in food production, injury and disease due to intense heat waves and fires, and shifts in the timing and spatial distribution of infectious diseases are likely to present the greatest risks.

Additional health risks: heat exposure

Secondly, the report documents evidence on an additional set of risks. Notably, the report reflects recent research on the significant possibility of “high end” climate scenarios, with some projecting warming of 4-7 degrees over much of the globe.

Under these conditions, human capacity to deal with heat will be exceeded in the hottest parts of the year in some regions, and it will no longer be possible to undertake unprotected outdoor labour or recreational activity.

Investment in preventative health

Thirdly, the latest report presents evidence that can guide the response to this challenge. It drew on studies that modelled for the first time the potential consequences of changes in climate alongside projected social and economic changes.

This research illustrates how climate change opposes the health gains achieved by social development, and may hold back progress in the poorest countries – but also shows how investment in preventive health programmes, in the context of strong and equitable socioeconomic development can also greatly decrease vulnerability, and potentially over-ride at least some of the health risks, in the short- to medium-term.

Improving health while cutting carbon emissions

Perhaps the largest advance is in documenting the rapidly growing evidence that well-planned actions to reduce greenhouse gas emissions can also bring very large health gains. The most obvious gains would come through reductions in air pollution, recently identified as the cause of approximately seven million deaths a year, or one in every eight deaths in the world.

The report documents the evidence that reducing emissions of short-lived climate pollutants such as methane and black carbon would not only slow warming, but could avoid 2-2.5 million deaths per year, globally. If converted into economic terms, the health gains associated with mitigation could offset much of the early cost of greenhouse gas mitigation.

This supports the conclusion that both climate-sensitive health risks, and the health benefits of cutting greenhouse gas emissions, should be central to any discussion on climate change.